The growing effort on the part of molecular biology in the studies of the composition and structure, as well as the laws of development of living organisms, and in solving vital problems of medicine, pharmacology, agriculture and the food industry accounts for rapidly expanding utilization of radioactive indication in establishing the laws governing biological processes in which biopolymers play a major role.
The existing systems for measuring the radioactivity of labelled biopolymers are either not automated or automated only to a limited degree. Many laborious operations at the preparatory and concluding stages of the work are done by hand, which accounts for an inadequate accuracy of measurements and may lead to radioactive contamination of the environment. There is also a danger that the personnel may be exposed to radiation.
An automatic system for measuring the radioactivity of labelled bipolymers would free the researchers from labor-consuming operation involving the handling of radioactive and toxic substances and would be beneficial in many other respects. The most important benefits are as follows. First, the working conditions would be improved, and the danger of radioactive contamination would be reduced. Second, research would proceed much faster, and the quality of radiochemical products would be improved. Third, an automatic system would make it possible to dispense with all the manual operations. The latter factor would account for a substantial increase in the accuracy of measurements and provide conditions for mathematical processing of the results, including computerized processing.
There is known a system for measuring the radioactivity of labelled biopolymers, comprising a cooling chamber which accommodates a set of containers containing aqueous solutions of biological samples which, in turn, contain biopolymers. The latter are precipitated on particles of diatomite in the presence of a coprecipitator, filtered, dissolved, and mixed with a scintillator. The mixture thus produced is fed into a detection chamber of a radioactivity measuring device (cf. Techniques in Protein Biosynthesis, vol. 2, edited by P. N. Campbell and I. R. Sangent, Academic Press, London & New York, 1969, pp. 157-163).
This prior art system comprises a set of containers for aqueous solutions of biological samples produced with the aid of separation techniques, for example, ultracentrifugation or chromatography of labelled biological preparations. The set of containers is arranged in the cooling chamber in order to preserve the structure of biopolymers and provide conditions for acid precipitation. For acid precipitation, the system is provided with a vessel for a solution of a coprecipitator, a vessel for a suspension of finely divided diatomite in a solution of trichloracetic acid, a pipette for successive proportioned delivery to the containers of predetermined amounts of the coprecipitator solution and the suspension of finely divided diatomite in the solution of trichloracetic acid. For filtering that part of the sample that is precipitated on particles of diatomite in the containers, the system includes a filtering means comprising a cellulose filter installed in a filtering funnel connected to a vessel for sucked-in filtrate, which, in turn, communicates with a vacuum pump. Diatomite suspension is introduced into the funnel by means of a pipette. In order to dissolve the biomaterial of the precipitate in an organic solvent, the system includes a vessel for an organic solvent and a pipette by means of which a proportioned amount of an organic solvent is introduced into a cell containing a cellulose filter with precipitate. For mixing the contents of the cell of a liquid scintillation counter, the system includes a vessel for a scintillator and a pipette for introducing the scintillator into the cell. For the transfer of cells with the mixture of the detection chamber, the system includes an automatic conveyer and a means for introducing cells into the detection chamber. For the removal of a cell's contents after radioactivity measurements and for washing and drying the cells, the system includes pincers for the removal of the cellulose filter, a vessel for the discharge of the mixture, a vessel for a washing fluid, and a drier for drying washed cells.
The prior art system under review is such that all the operations, except for radioactivity measurements, are done by hand, which accounts for a low efficiency of the measuring process which, in addition, takes too much time. The manual proportioned delivery of fluids and the manual transfers of the cellulose filter with the powdered precipitate into the cell of the liquid scintillation counter lead to errors and considerably reduce the precision of measurements. In addition, the numerous manual operations involved in the analysis of each sample are bound to distract the analyst's attention if he or she has to analyze a great number of samples; the result is a greater probability of an error, for example, a wrong order in which the operations are performed. The manual operations clearly lead to errors and may be the cause of radioactive contamination of the environment with dire consequences for the analyst and all working near him.